Developmental dyslexia is a health problem of enormous significance that is receiving increasing attention by researchers and educators. There is growing evidence that dyslexia may be a heterogeneous disorder and that the precise deficits in cognitive and linguistic processes manifested by dyslexics may vary with age. However, research on the nature of the disorder and on how it might be remediated has been hampered by a lack of detailed information regarding the processes by which dyslexics and normal children learn to read. A working conceptual model of reading is proposed that specifies several components of word processing that may be deficient in dyslexic children. Included are visual feature analysis, coding of letter, spelling pattern and word information, lexical access and semantic access. A series of cross-sectional studies examining the development of these word processing components in dyslexic and normal children is proposed. The development of accuracy, speed and automaticity on each of these components will be examined. In addition to the measures of component reading processes, several language subskills critical to learning to read will be investigated, including phonemic analysis, access to phonetic memory, lexical access and semantic retrieval. A third category of experiments will focus on the efficiency and flexibility of word decoding strategies in normal and dyslexic children at several age levels. Data from a number of the studies will be subjected to analyses to determine whether subtypes of reading and language disorders exist within the dyslexic population. The proposed experiments will provide information about the nature of reading deficits in dyslexic children and improve understanding of how reading skills develop in both the normal and dyslexic population.